Yet Another Low Carb Performance Study

Here’s another study which looked a performance on a Low Carb diet (Sawyer, JC, Wood, RJ, Davidson, PW, Collins, SM, Matthews, TD, Gregory, SM, and Paolone, VJ. Effects of a short-term carbohydrate-restricted diet on strength and power performance. J Strength Cond Res 27(8): 2255–2262, 2013).

For this study 16 men and 15 women were tested after a week on their habitual diet (40.7% carbohydrate, 22.2% protein, and 34.4% fat) and then a week later on a Carbohydrate Restricted Diet (CRD – 5.4% carbohydrate, 35.1% protein, and 53.6% fat). The CRD consisted of ≤50 g of carbohydrates per day.

The study was intended to determine if strength is lost with the short diet timeframe. The results were:

Subjects consumed significantly fewer (p < 0.05) total kilocalories during the CRD (2,156.55 ± 126.7) compared with the habitual diet (2,537.43 ± 99.5).

That can be seen here:

That’s less than 400 calories a day or 2800 calories for the seven days. This may be due to the following:

During the CRD, the researcher contacted each subject every 48 hours to answer any questions about the diet. Body weight was measured every 48 hours during the CRD to determine if any body mass changes had occurred. If a reduction in body weight occurred during the CRD, subjects were instructed to consume more calories to maintain body weight.

Continuing with the results.

Body mass decreased significantly (p < 0.05).

Fortunately this study showed the Total body water. This indicates that most of the FFM loss was due to water loss and seemed to be the only significant effect.

Both males and females had improved body fat composition.

Despite a reduction in body mass, strength and power outputs were maintained for men and women during the CRD.

One big advantage of this study was the goal of keeping calories enough to not have losses. That’s relevant to people on keto consuming maintenance calories.

A major weakness was the short duration of the study. We can’t say that seven days isn’t enough time for adaptation in some studies and that it is enough time in other studies, can we?

Another weakness was the lack of a control group. It would have been helpful to have part of the group stay on the habitual diet during the second period.

A third weakness was the same before and after the keto adaptation phase:

Before each testing session, subjects were required to refrain from performing resistance exercise for 48 hours.

A forth weakness was that:

Participants arrived at the Human Performance Laboratory after a 12-hour fast between the hours of 6:00 and 8:00 AM.

They were then fed a fat/protein meal.

The pre-exercise meal was provided to each subject 2 hours before the start of each exercise testing session. The meal consisted of 400 kcal. The meal included 250 ml of water, 2 hard-boiled eggs, 28 g of cheddar cheese, and a protein shake (Advant Edge Whey Protein; EAS, Inc., Abbott Park, IL, USA).

It seems likely that this meal would be more useful to the athletes after keto adaptation than before. Again a control group would have teased out this difference.

Conclusions

Most of the tests were very short duration – One Rep Maximums and short erg bicycles. Only one was to exhaustion and there was a lot of rest between sets (3 minutes). The Keiser power output was lower with the keto diet but judged to not be significant. That is a surprise to me since the change was greater than the error bars.

I would expect the keto athletes to do reasonably well with the short duration of the tests. Without a control group it is difficult to determine if the group should have gotten stronger or not.

 

Volek Talks about the FASTER Study

A video from 2015 where Dr. Volek talks about the FASTER Study (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.).

  1. Fat adapted athletes become “bonk proof” (see my post about that).
  2. Group of ultra-runners.
  3. More athletes volunteered than could be tested.
  4. Matched groups.
  5. LCD group was 70-20-10 F-P-C.
  6. HCD group was 25-15-60 P-F-C.
  7. Day 2 was three hours at 65% of VO2max (see my post about that). He later stated it ended up being at 64% of VO2max.
  8. They thought peak fat oxidation would be lower due to other studies documenting lower rates. They could have told from any low carb VO2max test that the peak rates were higher in Low Carb dieters.
  9. It looks as if they picked the 65% number based on this study (Achten J1, Gleeson M, Jeukendrup AE. Determination of the exercise intensity that elicits maximal fat oxidation. Med Sci Sports Exerc. 2002 Jan;34(1):92-7.).
  10. Volek showed the same graph from the VESPA article with the shift up and to the right of the fat oxidation curve (see my post about that).
  11. The statistically identical glycogen levels before, after and at the end of recovery were a surprise to Volek (as they are to me). Does fat allow the glycogen stores to refill? He thinks there is a chronic adaptation in LC athletes. It isn’t likely to be peripheral insulin resistance since the athlete’s muscles were biopsied to measure the glycogen levels, right? Alaskan sled dogs may provide a clue?
  12. Athletes were on LC for an average of 19 months.
  13. Gene expression differences between the two groups still being analyzed. Glycogen metabolism gene differences.
  14. LDL Cholesterol levels were much higher in LC athletes. HDL was also much higher in LC athletes.
  15. LDL Particle distributions were better in LC athletes (fewer smaller and more large LDL).
  16. Insulin Resistance scores were much better in LC athletes (top 1% of population).
  17. Half the high carb athletes have switched to low carb diet after the study.

 

 

Another VO2max Test – Van Wilder

I’ve got another friend, call him Van Wilder, who got his VO2max tested. He’s a 35 year old triathlete who has done an Ironman and marathons. He has about five years of running training. He did the Ironman fat adapted with very few carbs during the event. He’s recently gotten off the Low Carb bandwagon, at least partly. He is still lower carb.

Van Wilder’s VO2max came in at a respectable 59.8. That puts him within 5% of the elite athletes like Zach Bitter and Ben Greenfield. Van Wilder’s max fat oxidation rate is very close to the top levels measured in FASTER  (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.).

Here’s Van Wilder’s %VO2max vs Fat and Carbs Oxidation rates (in kcal/min).

At his peak he’s burning somewhere around 12 kCals a minute of fat. At the end Van Wilder is burning more than 22 kCals a minute of carbohydrates. His point where he’s burning 50% fat-50% carbs is at 80% of his VO2max. His peak fat oxidation is around 58% of VO2max. However, the point where he start burning carbs is relatively low at 45% of VO2max.

Compare his data with mine. I am fat adapted and only eat keto/low carb. I’m also 23 years older and not as trained by a long stretch.

Here’s the differences:

Parameter Van Wilder Doug LCS
Max Fat Oxid.
(kcal/min)
13 11
Max CHO Oxid.
(kcal/min)
22 22
%VO2max
Max Fat Oxid
58 53
%VO2max
Max CHO Oxid
100 100
%VO2max
50% Fat Oxid
50% CHO Oxid
80 78
%VO2max
Max Fat Oxid
Zero CHO Oxid
43 59

I would like to suggest that the main difference is found in the last row. My rate at which is expend no carbs and burn the most fat is at about 59% of my VO2max. Van Wilder’s point is about 43% of his VO2max.

Now my VO2max at 34.1 is significantly lower than Van Wilder’s at 59.8. And that probably explains a lot of the difference above. Van Wilder still looks to me like an efficient fat burner. Especially when compared to Damian Stoy.

Competition Fueling Strategies for Van Wilder?

What should the fueling strategy be for Van Wilder? Seems like he currently has the advantage of metabolic flexibility. He can certainly use fat for fuel at lower intensities.

 

VESPA and FASTER

Vespa has a graph on their site that shows %VO2max vs Fat oxidation in Low Carb and High Carb athletes from the FASTER study (Fat Adaptation: The Emerging Science from FASTER). Here’s the chart as it appears on the Vespa site:

I can’t find this graph in the FASTER Study paper  (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.).

But I do have some of the VO2max data tests from two of the athletes; Ben Greenfield and Damian Stoy. And Ben was LCD and Damian was HCD. So we should be able to check the graph using their data.

Here is Ben’s curve:

Here is Damian’s curve:

Peak Values

Damian’s peak rate of fat oxidation at around 0.35 g/min was about one-third of Ben’s top rate of around 1.1 g/min. So in this regard the curves do match the relative magnitudes in the Vespa graph.

Shifted Values?

The VESPA graph for the LCD vs the HCD shows a shift to the right for the peak fat oxidation for LCD as compared with HCD. In fact, the VESPA graph shows the peak of the LCD at 70% of VO2max and shows the peak of the HCD at 50%.

This doesn’t match Ben’s data at all. Ben’s fat oxidation peak is clearly around 55% of VO2max.

There is a small shift to the left for vegan Damian Stoy. His peak is somewhere around 45%.

I want to see the other data to see if Ben is at one end of the LC data but he pretty clearly doesn’t match the %VO2max vs maximum fat oxidation rate that the VESPA graph implies.

Why Should I Care?

I care because my own data matches Ben Greenfield’s data.

FASTER Again – Checking a number on Ben Greenfield’s data

Ben Greenfield was a participant in the FASTER study (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.).

Ben’s VO2max number was 61.1. The FASTER study was supposed to be performed at 64% of VO2max. For Ben that should have been 61.1 * 0.64 = 39.1. At that rate Ben would have been using 67% fat and 37% fat as his fuel for the three hour treadmill test.

But that’s not what Ben’s actual data shows.

Ben’s VO2 numbers were 35.8-37.0. Now that’s not that much different, but in this case it’s a significant difference. At 36.5 Ben is at a much different fuel mixture (80% fat and 20% carbs).

I am not suggesting there was any cheating here but the numbers really didn’t match the words of the study.

And repeated here:

And here:

There may be a clue here:

Was Ben adjusted downward? Even if he was the adjustment should have been done based on the VO2max testing. The number should have been 39.1 not 36. Here’s Ben’s VO2max testing result.

I am concerned about this difference. I’d like to know what’s up. There’s a huge difference between 2/3 Fat to 1/3 Carb and 4/5 Fat to 1/5 Carb. Especially over three hours. Especially when you end the race with low glycogen stores.

The details matter.

 

Slower But Fitter?

An interesting study put a group of endurance athletes on a Ketogenic diet and measured their performance as well as body composition changes (Zinn C, Wood M, Williden M, Chatterton S, Maunder E. Ketogenic diet benefits body composition and well-being but not performance in a pilot case study of New Zealand endurance athletes. J Int Soc Sports Nutr. 2017 Jul 12;14:22.). The study concluded:

All athletes increased their ability to utilise fat as a fuel source, including at higher exercise intensities.

Mean body weight was reduced by 4 kg ± SD 3.1 (p = 0.046; effect size (ES):0.62), and sum of 8 skinfolds by 25.9 mm ± SD 6.9; ES: 1.27; p = 0.001).

But how was their performance?

Mean time to exhaustion dropped by ~2 min (±SD 0.7; p = 0.004; ES: 0.53). Other performance outcomes showed mean reductions, with some increases or unchanged results in two individuals (VO2 Max: -1.69 ml.kg.min ± SD 3.4 (p = 0.63); peak power: -18 W ± SD 16.4 (p = 0.07), and VT2: -6 W ± SD 44.5 (p = 0.77).

Was this an adaptation problem?

Athletes reported experiencing reduced energy levels initially, followed by a return of high levels thereafter, especially during exercise, but an inability to easily undertake high intense bouts. Each athlete reported experiencing enhanced well-being, included improved recovery, improvements in skin conditions and reduced inflammation.

In the end the athletes likes the health benefits even with the performance losses.

Another VO2max Test

I have a friend, let’s call him Moe. Moe is 30 years old. Moe is not a low carb dieter. Moe has been inconsistent in his training for the past two years. Moe has recently taken up running again. Moe’s MAF number is 180 – 30 -5 = 145. Use the Heart Rate Calculator to see the numbers.

Moe took the same Vo2max test that I did at WVU Human Performance Lab. Here’s Moe’s fat/carb oxidation curves.

If Moe does MAF Heart Rate training at 135-145 is heart rate would be approaching his cross-over of fat/carbs kcals per minute. However, Moe wants to burn the maximum number of calories so he runs near his max heart rate. When he runs at a high heart rate, Moe is burning carbs and not much fat. Moe could adopt a low carb diet and run slower with the positive effect of increased fat loss and no need to burn carbohydrates.

Me vs Moe

I am 28 years older than Moe. Here’s my curve with my MAF Heart Range noted.

My max fat oxidation rate is around 11 kcal/sec. Moe’s max fat oxidation rate is around 9 kcal/sec. Moe’s max carb oxidation rate is 16 kcal/min vs my 24 kcal/min.

 

MAF and Resistance Training

I’ve spent a little bit of time thinking about the compatibility of MAF Heart Rate Training and weightlifting – generically termed resistance training (RT). Since the activity is relatively short duration and the heart rate isn’t past the MAF Heart Rate it seems on the surface like it would be compatible to do both.

One thing to consider is that VO2max testing is done on a treadmill which increases the speed and angle every couple of minutes. Resistance training lasts for seconds. The Rate of Perceived Exertion (RPE) of the VO2max testing isn’t all that hard until it gets towards the end of the test. The RPE of weightlifting is substantial under significant loads so using RPE as a test this would indicate that there is an issue.

My measurement for whether an activity is aerobic or anaerobic is the Respiratory Exchange Ratio (RER). RER is correlated to heart rate in the VO2max test but rarely considered in RT. There is a study which looked at RER in RT (Scott. Quantifying the Immediate Recovery Energy Expenditure of Resistance Training. The Journal of Strength and Conditioning Research · April 2011) in terms of Excess Postexercise Oxygen Consumption (EPOC). To review:

The respiratory exchange ratio (RER) is calculated as steady-state CO2 produced divided by steady-state O2 consumed and is typically defined from values of 0.70 representing total fat oxidation to 1.00 representing total glucose oxidation.

Here’s the RER data from the study for RT. Note the RER values are all well over 1.0 which indicates anaerobic exercise range.

Another interesting comment helps explain the RER values above 1.0:

During and after exercise, RER values above 1.00 are generally thought to be the result of nonrespiratory CO2 production: The bicarbonate buffering system, for example, involves the removal of hydrogen ions with concomitant CO2 production and hyperventilation blows off ‘‘extra’’ CO2. Yet a true measure of the RER is best found only when the system is in a steady state of gas exchange.

To the subject at hand:

Rapid glycolysis (as part of anaerobic metabolism) ceases when muscle contraction stops so that recovery is considered to be aerobic in nature. If this is true, both fatty acid and lactate oxidation may play a significant role in fueling the immediate energy expenditure needs of recovery. Unfortunately, substrate oxidation immediately postexercise and particularly after anaerobic-type exercise has not been studied well enough to draw specific conclusions. Because of this, it must be assumed here that when muscle contraction immediately stops, glycolysis is limited to the point where fat and lactate are the predominantly oxidized fuels.

 

FASTER Study Interviews

Zach Bitter was a participant of the FASTER study (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.) Our BLOG post about Zach in the study (Zach Bitter – Another FASTER participant). Jeff Volek was one of the scientists doing the FASTER study. Endurance Planet interviewed them together in a three part series.

Jeff and Zach speculated about how long this could go saying that perhaps 5 hours would have been a better test. Based on Ben’s fat oxidation rate I’m not sure that would have been a good idea. Ben’s fat was dropping in a linear form but his carbohydrate oxidation was speeding up fits to a 2nd order poly.

Here is another interview with Zach about FASTER (Primal Endurance Podcast).

FASTER10 – Ben Greenfield – Three Hour VO2 testing

The main test that Ben test was a three hour treadmill test in the FASTER study (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.).

In Ben Greenfield’s case the activity was done at an average of 60% of VO2max. At that level of effort Ben got 85% of his energy from fat and 15% from carbohydrates. Here’s the data from the three hour treadmill test.

%VO2max FATcal CHOcal %cal-fat
58% 10.013 3.1007 76%
61% 12.394 1.2341 91%
59% 11.722 1.4985 89%
60% 11.645 1.8409 86%
61% 11.154 2.5325 81%
Average = 60% 11.386 2.046 85%

An interesting question is the trend of the oxidation over the three hours. Here the graph of the data is interesting. The blue line is energy from fat and the brown line is energy from carbs. The x-axis is time. Note that as time proceeds Ben is drawing less and less energy from fat and more and more from carbohydrates. The R^2 values show a strong significance.

Ben’s individual Fat Oxidation data is not too far off of the data from the study. The average makes it look as if a person could continue on seemingly forever but Ben’s data shows that is not the case.

Similarly, his carb oxidation rate is very similar to the average since it shows a steady climb up.

It should also be recalled that although fat provides 9 calories per gram and carbohydrates provide 4 calories per gram fat is burned less efficiently for energy – about 10% less efficient than carbohydrates.